Aircraft floats of various types have been attached to the undercarriages of aircraft to allow the aircraft to operate from bodies of water. The three principal types of float that are in common use are aluminum floats, fiberglass floats, and inflatable floats, with the type of float that may be used for a given aircraft depending, in part, upon the aircraft's size and classification. General aviation aircraft, which are all "type certified" by the Federal Aviation Administration (FAA), are commercially assembled aircraft such as corporate executive jets and Cessna light airplanes. Experimental aircraft must be home built and are typically sold as kits. Ultralight aircraft are usually tubing and fabric construction and, again are typically sold in kit form and home built.
Aluminum aircraft floats are typically manufactured from sheets of aircraft grade aluminum riveted and/or bonded onto a series of bulkheads and stringers to form a float having a predetermined shape. Though in widespread use, these floats have a number of drawbacks. First, the aircraft aluminum utilized in the manufacture, and the labor expended in assembling the floats, makes these floats fairly expensive. Second, the use of rivets along the seams on the underside of the float increases the chance that water will seep into the inside of the float. Such seepage can create a dangerous situation due to unpredictable shifts in the center of gravity of the aircraft. In some designs, a water-proof closed-cell foam is utilized to at least partially fill the inside volume of the float to prevent water seepage. However, these foams add weight to the floats and further increase their cost.
Fiberglass floats, such as those described in U.S. Pat. No. 3,208,421, are often utilized on experimental and ultralight aircraft. These floats are typically manufactured either by forming two mating fiberglass shell pieces in two female molds and subsequently bonding the shell pieces together, or by forming a water-proof foam into the desired shape and forming the fiberglass over the foam. Fiberglass floats also have a number of drawbacks. First, the cost of manufacturing fiberglass floats is relatively high as a result of the labor expended in forming the completed float. Second, fiberglass is not very impact resistant and can crack and leak if subjected to impact from rocks, logs, or other underwater obstructions. Third, the seam between the two pieces of the float creates a fault line that is subject to cracking and water leakage. Fourth, the use of foam within many of these floats increases the weight of such floats. Finally, the nature of the fiberglass process creates a hazard to manufacturing workers due to the friability of the fiberglass and the potentially toxic chemicals used to promote bonding.
Inflatable floats, such as those described in U.S. Pat. No. 4,697,762, typically include an outer shell manufactured of a tough fabric and an interior portion that is segregated into a plurality of inflatable interior chambers or bladders. In operation, the chambers are inflated with air until the chambers press against the outer shell to form a relatively hard surface upon which the aircraft may land. Inflatable floats, like the aluminum and fiberglass floats described above, have a number of significant drawbacks. First, water may penetrate the outer shell and occupy the spaces between the inflatable interior chambers causing the same unpredictable changes in weight and shifts in the center of gravity of the aircraft that may occur with aluminum and fiberglass floats. Second, the tough fabric on the outside of the float is prone to absorbing water and carrying water on its upper surface, thus increasing the weight of the aircraft during take-off. Finally, one or more chambers of an inflatable float may deflate unexpectedly, creating a potentially hazardous situation for the pilot.
Therefore, there is a need for an aircraft float that may be utilized with experimental, ultralight, and light general aviation aircraft, is less expensive than existing aluminum and fiberglass floats, is lighter than existing aluminum and fiberglass floats, and is more impact resistant than existing fiberglass floats.